Peroneus (fibularis) Longus Muscle
Peroneus (Fibularis) Longus
Action – Eversion and plantarflexion of the foot
– Eversion – the foot moves towards the side of the smallest toe
– Plantarflexion – pointing the toes downwards
Origin – head and proximal shaft of the fibula
Insertion – medial cuneiform and base of the 1st metatarsal (plantar surfaces)
Nerve – superficial peroneal (fibular) nerve L5, S1
Peroneus longus is located on the outer part of the lower leg, along with peroneus brevis (short) and peroneus tertius (third). These peroneal muscles may also be known as fibularis longus, brevis and tertius. The name changed to fibularis in the international standard for human anatomy as the muscles are attached to the fibula bone (perónē in Ancient Greek), and also to avoid confusion with the perianal region – important for treatment purposes! Most people still use the term peroneus though, as old habits die hard.
The three muscles are often grouped together because they evert the foot. Peroneus longus is also a key stabiliser of the ankle joint, balancing against the ankle invertors (move the foot towards the big toe side). It is a strong muscle that can withstand the forces of running and jumping.
Injury or dysfunction in the peroneus longus muscle may cause pain or discomfort in the lower leg, ankle or foot (especially on the outside, refer to above picture). This can cause difficulty with walking and running. The muscle may become weakened or strained following the most common ankle injury, an inversion sprain. Symptoms may need to be differentiated from dysfunction of peroneus brevis and tertius, hip or knee joint dysfunction referral or nerve entrapment or irritation from the lower back.
Tie a resistance band to a sturdy object. Place your foot in a loop at the other end of the band, keep your lower leg still and rotate your foot outwards, stretching the band using only your foot. Hold for 2-3 seconds then rest. Repeat 10-15 times.
Invert the ankle with gentle over pressure. Note, stretching of the peroneal muscles is generally NOT indicated as over stretching can lead to chronic recurrent ankle sprains.
Lie on your side with a foam roller under the outside of your lower leg. Pressure can be modified by adjusting your bodyweight on your arms and other leg. Slowly move the affected leg along the foam roller, pausing for around 30 seconds on any tender spots.